Agricultural combines traditionally have a grain storage bin wherein threshed and cleaned grain is stored. As the combine harvests and threshes crop materials in the field, grain is continuously delivered to the storage bin or tank. As will be appreciated, continuous field operation of a combine is generally limited by the capacity of the storage bin to hold the cleaned grain. When the storage bin is full, the combine operator must normally cease the harvesting and threshing operation to unload cleaned grain from the storage bin to a receiving vehicle.
Unloading conveyors for harvesters, such as combines, typically take the form of an unloading tube in which a power driven material moving member or auger is disposed. The unloading conveyor tube is mounted to a frame of the combine for movement between a transport position, whereat the unloading tube is positioned generally parallel to the frame of the combine, and an unloading position whereat the unloading tube extends away from the combine frame to facilitate discharge of material into a truck or other suitable vehicle arranged along side the combine. The unloading tube is swung between positions under the influence of a power driven actuator. The auger within the unloading tube is operated under the influence of a drive mechanism including a clutch which is shiftable between clutch-engaged and clutch-disengaged positions.
Unloading of the storage bin is normally activated by engaging a switch which causes the unloading tube to automatically move between positions while conjointly controlling operation of the auger. Should an unloading operation be conducted while the combine continues to harvest and thresh crop material, this requires the operator to direct his attention to several functions at one time. That is, the operator must continually monitor the crop material which is being harvested at the front of the combine, scan the numerous monitors which display various indications on a control panel, while observing the movement of the unloading tube from an inboard to a fully outboard position for purposes of unloading the storage bin.
For any of several different reasons, the operator may temporarily discontinue the harvesting operation and shut off or shut down the combine. The cab region of the combine has relatively tight space constraints therein partially because of the number of various controllers that are arranged in and about the operator's seat for convenient access to the operator. Occasionally, as the operator leaves the cab region, one or more of the switches and/or controllers can be inadvertently moved from one position to another. Alternatively, the operator's attention may be diverted such that the operator is unmindful of changing a switch at the last moment before leaving the cab region of the combine. Thus, when the operator returns to the cab region of the harvester, he may be unaware or forgetful of any change in the various switches and controllers arranged in and about the cab region. Accordingly, when the engine is again started, the change in state of the various switches and/or controllers can cause unexpected operation of the unloading conveyor.
Following an operator's return to the combine, it is not uncommon for the unloading tube to inadvertently move under the influence of its actuator upon restarting of the engine because the operator inadvertently moved the switch upon leaving the cab region, re-entering the cab region or because the operator failed to remember the last setting of the switch. The problems associated with unexpected movement of the conveyor tube are apparent to those skilled in the art. Moreover, and for many of the same reasons discussed above, the unloading conveyor may move material through the unloading tube because of an inadvertent setting on a switch or lever. Thus, often times, clean grain is lost in the field. Of course, if operation of the auger is not quickly detected, there can be a considerable loss of clean grain which is exhausted from the unloading conveyor or tube.
Thus, there is a need and a desire for a combine control system for preventing inadvertent movement of the conveyor tube between positions and for preventing inadvertent discharge of cleaned grain material following an interruption of power to the controllers used to condition the unloading conveyor system for operation.